The importlib.resources module has several modules on which it relies (_adapters, _legacy, simple) and some classes in other modules shared by other parts of importlib (namely abc).

Because these implementations overlap, it adds difficulty in maintaining the `importlib_resources` backport, which must maintain these modules but keep them separate from the unrelated functionality in other parts of importlib.

In an earlier refactoring, `importlib.metadata` was refactored into its own package (https://github.com/python/cpython/pull/25565). This refactoring had benefits of making it clearer which functionality of importlib was related to metadata and which was not.

I'd like to do the same for importlib.resources.

The main complicate